In wireless communications multi-path propagation is a phenomenon that results in radio signals reaching the receiving antenna by two or more paths. Multi-path propagation may be caused by ionosphere reflection and refraction or by reflection from terrestrial objects such as mountains and buildings. Multi-path propagation may produce errors in the receiver due to undesired constructive and destructive interference and phase shifting of the received radio signals. The resulting intersymbol interferences degrade the quality of communications.
Radio receivers, e.g. UMTS modems or Rake receivers, estimate a multi-path profile of the radio channel to compensate for the undesired effects of multi-path propagation. Weak paths of the multi-path signals estimated by the radio receiver however generate more noise than they help in decoding and thus should be rejected. Field tests have shown that weak paths close to a strong path exhibit a lot of interference from the nearby strong path and thereby degrade the performance of the radio receiver. The receiver may increase a threshold for selecting paths from the multi-path profile to exclude the weak paths from further processing. Increasing the threshold, however, decreases the accuracy of the radio receiver as independent paths which are not interfered by nearby paths are suppressed too.
For these and other reasons there is a need for an improvement in radio receivers that estimate a multi-path profile.